Transformer tank



Dec. 17, 1957 D. B. LEIGHTNER ETAL 2,816,947

TRANSFORMER TANK 2 Sheets-Sheet 1 Filed June 26, 1953 INVENTORS DONALD E. LEIGHTNER By ROBERT R. HAYES TRANSFORMER TANK 2 Sheets-Sheet 2 Filed June 26, 1953 3 5 \\\\A 0 2 v 7 a f: w: :1 5% n n 7 m n n INVENTO Rs EIGHTNE'R United States Patent TRANSFORMER TANK Donald E. Leightner and Robert R. Hayes, Welland, Ontario, Canada, assignors to Reliance Electric 6': Engineering (Canada) Ltd.

Appiication June 26, 1953, Serial No. 364,396

17 Claims. (Cl. 174-18) The invention relates in general to non-conductive tanks for electrical transformers and more particularly to a transformer tank consisting of reinforced thermosetting resins wherein all parts of the transformer tank are nonconductive.

The customary form of distribution transformers is to use a steel tank and cover and porcelain bushings through which terminals extend to provide electrical connection to the high voltage windings on the transformer inside the tank. Distribution transformers are those operating from high voltage distribution lines which may be two thousand three hundred volts or up to thirteen thousand eight hundred volts. The transformer steps down the voltage to consumable voltage level, such as one hundred ten to four hundred forty volts. The prior art steel tank is weatherproof since the distribution transformer generally is mounted outdoors at the top of a pole. Further, the distribution transformers may be filled with a dielectric oil to increase the dielectric constant. Because of the steel tank, there must be a considerable spacing between the high voltage windings and the inner surface of the tank in order to avoid flashovers. Further, the porcelain bushings used at the high voltage terminals generally are of considerable radial length so that the distance between the end of the terminal and the steel tank is greater than the voltage striking distance in air from metal to metal at the high voltage operation. Still further, the prior art bushings were skirted or petticoated to increase the voltage creepage distance to a permissible minimum. This made a large, bulky, and cumbersome transformer design because the tank had to be considerably larger than necessary merely to enclose the transformer proper, and the high voltage bushings radially protruded a considerable distance Which made a still larger packing case and shipping space. Further, the larger tank meant a larger quantity and weight of dielectric oil.

An object of the invention is to provide a small compact transformer of a given kva. rating.

Another object of the invention is to provide an insulated weatherproof enclosure for a transformer.

Another object of the invention is to provide an oii filled transformer that requires a minimum amount of dielectric oil.

Another object of the invention is to provide a glass fiber reinforced thermosetting resin transformer tank and attachments.

Another object of the invention is to provide a weatherproof enclosure for a transformer wherein the tank, cover, mounting bracket, lifting hooks, and high voltage bushings are all formed from a non-conductive and non-magnetic material.

Another object of the invention is to provide a mount ing arrangement for a transformer within a tank wherein the transformer is resiliently held in place even though the tank may be roughly handled and turned on its side or top.

Another object of the invention is to provide a transformer wherein the distance between the high voltage windings and the tank as well as the radial distance of the high voltage bushings is less than the voltage striking distance from metal to metal in air.

Another object of the invention is to provide a transformer tank which is corrosion resistant, weather resistant, light weight, permanently colored, and which has no stray load losses.

Another object of the invention is to provide a transformer tank which has bushings which are virtually unbreakable and much shorter than conventional practice.

Another object of the invention is to provide a transformer tank which has integral lugs and ribs on the inner surface to establish guides for centering and restraining upward and sideward movements of a transformer therein.

Another object of the invention is to provide a transformer tank which complies with all standards established by various standards associations, yet which is smaller and lighter than the prior art metallic tanks.

Other objects and a fuller understanding of this invention may be had by referring to the following description and claims, taken in conjunction with the accompanying drawings, in which:

Figure 1 is an exterior side view of the complete transformer;

Figure 2 is atop view with the cover removed; and

Figure 3 is a sectional view on the line 33 of Figure 2.

The Figures 1, 2, and 3 show a weatherproof enclosure 11 for a transformer 12. The enclosure 11 includes a tank 13 and a cover 14. The tank 13 is generally cylindrical and has a flat bottom 15. The tank 13 has an upper portion 16 terminating in a lip 17 at the upper open end of the tank.

The cover 14 is circular and slightly domed to shed rain. The cover 14 has a gasket recess 18 containing a gasket 19. A down turned rim 20 on the edge of the cover 14 radially locates the cover 14 on the tank 13. A one-piece split compression clamp 21 is generally U- shaped in cross section and has a cam acting handle 22 which fastens the cover 14 to the tank 13 and compresses the gasket 19 to effect a fluid seal. Four equally spaced notches 23 on the cover 14 are complementary with four equally spaced notches 24 on the tank and provide rain water passageways.

A mounting bracket 29 includes a body portion 30 and four protruding cars 31. The body portion 30 is curved to a partial cylindrical form along a longitudinal axis to conform to the outer surface of the tank 13. The four mounting cars 31 lie generally in a plane which is parallel to the axis of the tank 13 and which plane lies outside the surface of the tank 13. The mounting ears have holes 32 therein. Two lifting hooks 33 are equally spaced around the periphery of the tank 13 near the upper portion 16. These lifting books have a body portion 34 and a foot 35 which lie inside and engage a continuous band 36. The continuous band 36 also encircles the upper portion of the mounting bracket 29 to fasten the lifting hooks and the mounting bracket to the tank 13. A second continuous band 37 encircles the tank 13 and lower portion of the mounting bracket 29. First and second high voltage bushings 41 and 42 are attached to the outer surface of the tank 13 at the upper portion 16. Each of the bushings 41 and 42 surrounds a high voltage terminal 43 which extends through the wall of the tank 13 and makes a fluid seal therewith. Insulated knobs 44 threadably engage the terminals 43 in order to clamp an external conductor 45 to the terminal 43. First, second, and third low voltage terminals 46, 47, and 48 extend through the wall of the tank 13, also in the upper portion 16. No bushings are provided at the low voltage terminals 46 to 48 because of the low voltages involved. These terminals are provided with insulated knobs 49 threadably connecting with the terminals in order to connect to external conductors 50.

The tank 13 has an inner wall surface 55 which has a slight taper of approximately two degrees flaring outward at the top. A first pair of longitudinalribs 56 is integrally formed with the inner surface 55. These ribs 56 are closely spaced and extend substantially the entire length of the tank 13. A second pair of longitudinal ribs 57 is disposed generally diametrically opposite the first pair of ribs 56. A first pair of lugs 58 is integrally formed with the tank at the junction of the side wall and bottom 15. The pair of lugs 58 is spaced farther apart and straddles the pair of ribs 56. A second pair of lugs 59 is provided generally diametrically opposite the lugs 58. Each of the lugs 58 and 59 has a recess formed by a'bottom' wall 60, a side wall 61, and an end Wall 62. These three walls 60, 61, and 62 are mutually perpendicular. The tank 13, cover 14, compression clamp 21, mounting bracket 29, lifting hooks 33, bands 36 and 37, and the high voltage bushings 41 and 42 are formed from a glass fiber reintorced thermosetting or self-setting resin. An example of a thermosetting resin which may be used is apolyester resin formed by the reactive product which is obtained when a dicarboxylic acid and a polyhydric alcohol are reacted together. I

The tank 13 with the lip 17, notches 2'4, ribs 56 and 57, and lugs 58 and 59 maybe integrally molded at one time. The two degree taper permits the tank to be removed from male and female molds. recess 18, notches 23, and rim may also be completely molded at one time. The lifting hooks 33 may be glass fiber reinforced thermosetting resin which will provide adequate strength for lifting the entire weight of the enclosed transformer 12. The mounting bracket 29 may have either glass fiber reinforcing or it may include expanded metal 63, especially at the end portions joiningthe cars 31. The thermosetting resin has a voltage dielectric strength of four hundred volts per mil and with the thickness of the thermosetting resin being at least an eighth or perhaps three sixteenths of an inch on each side of the expanded metal of sufficient dielectric strength to preclude any are jumping through to the expanded metal 63.

The continuous bands 36 and 37 may be formed by glass fiber roving dipped or otherwise saturated in the thermosetting resin and then wound around the tank 13, lifting hooks 33, and mounting bracket 29. A metal band mold may be used temporarily during the setting process in order to cause the bands 36 and 37 to blend into the tank and to obtain a smooth surface on the bands. The high voltage bushing s 41 and 42 have a partially cylindrical contour on the inner surface 64 thereof so that they fit tightly against the exterior wall of the tank 13. They may be connected to the tank 13 by using additional thermosetting resin. Low voltage bushings similar to but smaller than the high voltage bushings 41 and 42 could be used; however, they are not necessary because of the low voltage operation and the fact that the entire tank 13 is non-conductive and non-magnetic.

The transformer 12 is completely enclosed by the tank 13 and cover 14. The transformer 12 includes a laminated permeable core or frame 71 which carries first and second coils 72 and 73. These coils contain high and low voltage windings with the high voltage windings connected. by high voltage leads 74 and 75 to the terminals 43. Channel-shaped top and bottom core or frame clamps 76 and 77 straddle the core 71 and are fastenedtogether and to the core 71 by straps 78 and bolts 79. The bottom core clamp 77 is generally rectangular, as shown in Figure 2, and the four corners thereof'rest'upontheibottorn walls 60 of the lugs 58*and 59. Further, the side walls 61 and end walls-62in the lugs 58 and 59 prevent shifting of the core clamp '77 and core 71 either right-and left or up and down, as viewed in Figure 2. Each of the- The cover 14 with the gasket bolts 79 is engaged by a nut 80 and under the nuts 80 lie plates 81 and resilient springs 82. The springs 82 have an upwardly extending tongue 83 which digs into the sloping side walls of the ribs 56 and 57. The ends of the tongues 83 are slightly spaced from the inner wall surace 55 so that a screwdriver or similar instrument may be used to separate the tongues from the ribs so that the transformer 12 may be removed from the tank 13. When in the position shown. in the drawings, the tongues 83 dig into the ribs 56 and 57 to restrain upward movement of the transformer 12 relative to the tank 13. The plates 81 are relatively stiff and lie closely adjacent the ribs 56 and 57 to restrain right and left or up and down movements of the top of the transformer core 71 relative to the tank 13. Thus, the ribs 56 and 57 and lugs 58 and 59 may be considered as locator means for the core 71, because the co-operation between the bottom core clamp 77 and the lugs 58 and 59 and the co-operation between the plates 81, springs 82, and ribs 56 and 57 completely restrains all movements of the transformer 12 relative to the tank 13. Thus, the enclosed transformer will with-stand rough handling and will withstand treatment of being placed on its side or cover.

A ground terminal 86 is provided with a handle 87 and located near the bottom of the tank 13. The terminal 86 extends through the wall of the tank and has a connection 88 to a grounding wire 89. The grounding wire 89 extends under the bottom core clamp 77 and through a hole 90 in a non-conducting longitudinally disposed strip 91. The wire 89 extends upwardly to the top of the tank and lies between the strip 91 and the inner wall surface 55. Near the upper portion 16 of the tank 13 it extends through a hole 92 in the strip 91 and attaches to the bolt 79. This will provide a ground connection for the core '71. The fact that the grounding wire 89 extends up to the top of the core 71 permits easy connection and disconnection thereof for assembly purposes. The tank 13 has sufiicient depth to house a conventional tap switch 93 which may be used for slightly varying the turns ratio. The tank 13 is adapted to be filled with oil up to a line 94.

It will be noted, especially in Figure 2, that the high voltage windings, such as at the corner 95, extend quite closely to the inner wall surface 55. The fact that the tank 13 is made from non-conducting and non-magnetic material permits this close spacing which is less than the voltage striking distance from metal to metal in either air or oil as defined by various standards associations. These standards associations prescribe definite minimum safety requirements for voltage striking distance and voltage creepage distance. Further, the bushings 41 and 42 have a radial length which is considerably less than the voltage striking distance from metal to metal in air. Further, these bushings do not need to be petticoated in order to increase the voltage creepage vdistance since the entire surface of the tank is an insulator; and there is thus a large creepage distance on the surface of the tank to add to the creepage distance on the high voltage bushings. The cover 14, clamp 21, and continuous band 36 are all made of thermosetting resin; hence, there is no metallic path near the high voltage bushings which would cause initiation of an arc. The fact that the tank 13 may closely encompass the coils 72 and 73 permits a considerably smaller volume of dielectric oil which is a saving in cost and a saving in weight. Besides permitting a smaller diameter tank by using dielectric material, the short length of the high voltage bushings provides another means for establishing a small and compact complete transformer. This saves'space in shipping and reduces shipping and handling charges. The transformer, while generally used outdoors, may be used.indoors,,such as in locations which have a corrosiveatrnosphere; and the thermosetting resins of the tank will withstand such corrosive atmosphere much betterthan the conventional steel tank. The color of thethermosetting resin is permanently infused in the resin; and hence, the tank never needs painting or other mass? protective surface coating. The fact that the tank is nonmagnetic completely eliminates all stray load losses in the tank, thus resulting in a more efficient transformer. A name plate 96 may be bonded to the exterior wall of the tank or molded into the wall of the tank.

The tank has been described as formed from glass fiber reinforced thermosetting resin; however, other reinforcing material may be used; and other resins, such as self-setting resins, or other insulating material, may be used in the tank and attachments.

Although this invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

What is claimed is:

1. A weatherproof housing for apparatus having high voltage windings thereon, comprising a weatherproof enclosure including a tank and a cover therefor, a mounting bracket mounted on one side of said tank to provide a means for cantilever mounting of the complete apparatus, terminals extending through high voltage bushings provi-ding electrical connection from the inside to the outside of the tank, locator means connected to the inside of said tank, said locator means, tank, cover, mounting bracket, and high voltage bushings being formed from dielectric material, spring means connected to said apparatus and constructed of material harder than said dielectric material to resiliently engage and dig into said locator means to hold said apparatus in place in said tank, said high voltage bushings having a radial length exterior of said tank which radial length is less than the voltage striking distance at said high voltage operation, and said windings adapted to be spaced from the inner wall surface of the tank a distance less than the voltage striking distance in air from metal to metal at said high voltage operation.

2. A weatherproof housing for apparatus having a high voltage winding thereon, comprising, a tank and a cover therefor, terminals extending through high voltage bushings providing electrical connection from the inside to the outside of the tank, locator means connected to the inside of said tank, said locator means, tank, cover, and high voltage bushings being formed from dielectric material, spring means connected to said apparatus and constructed of material harder than said dielectric material to resiliently engage and dig into said locator means to hold said apparatus in place in said tank, said high voltage bushings having a radial length exterior of said tank which radial length is less than the voltage striking distance in air from metal to metal at said high voltage operation, said winding adapted to be spaced from the inner wall surface of the tank a distance less than the voltage striking distance in air from metal to metal at said high voltage operation, and said tank adapted to be filled with a dielectric oil.

3. A housing for electrical apparatus having a frame, comprising a tank and cover to close same, first and second pairs of diametrically opposed closely spaced longitudinal ribs on the inner surface of said tank, said tank, cover and longitudinal ribs being formed from dielectric material, a top frame clamp engaging said apparatus frame, first and second leaf springs clamped by first and second stiff members at opposite ends of said top frame clamp with said leaf springs resiliently engaging said first and second pairs of ribs to centrally locate the top of said frame and restrain upward movement thereof and with said stiff members restraining sideways movement of said frame, and said apparatus extending to within a distance from the inner surface of said tank which is within the voltage striking distance in air from metal to metal of the operational voltage of the apparatus.

4. A housing for electrical apparatus having a frame,

comprising a tank and cover to close same, first and sec ond pairs of diametrically opposed closely spaced longitudinal ribs on the inner surface of said tank, first and second pairs of diametrically opposed widely spaced lugs on the inner surface of the bottom of said tank, said pairs of lugs straddling said pairs of ribs, said tank, cover, longitudinal ribs, and lugs being formed from dielectric material, a top and a bottom frame clamp for engaging said apparatus frame, said bottom frame clamp being generally rectangular and engaging each of said first and second pairs of lugs to centrally locate the bottom of said frame, first and second leaf Springs clamped by first and second stiff members at opposite ends of said top frame clamp with said leaf springs resiliently engaging said first and second pairs of ribs to centrally locate the top of said frame and restrain upward movement thereof and with said stiff members restraining sideways movement of said frame, and said apparatus extending to within a distance rom the inner surface of said tank which is within the voltage striking distance in air from metal to metal of the voltage of operation.

5. A housing for electrical apparatus having a frame, comprising a tank and cover to close same, first and second pairs of diametrically opposed closely spaced longitudinal ribs on the inner surface of said tank, first and second pairs of diametrically opposed widely spaced lugs on the inner surface of the bottom of said tank, said pairs of lugs straddling said pairs of ribs, first and second high voltage bushings located near the top of said tank, low voltage terminals located near the top of said tank and spaced from said high voltage bushings, electrical terminals extending through said tank at each of said high voltage bushings, said tank, cover, longitudinal ribs, lugs, and bushings being formed from dielectric material, a top and a bottom frame clamp adapted to engage said apparatus frame, said bottom frame clamp being gen erally rectangular and engaging each of said first and second pairs of lugs to centrally locate the bottom of said frame, first and second leaf springs clamped by first and second stiff members at opposite ends of said top frame clamp with said leaf spring resiliently engaging said first and second pairs of ribs to centrally locate the top of said frame and restrain upward movement thereof and with said stiff members restraining sideways movement of said frame, said apparatus adapted to be spaced from the inner surface of said tank a distance less than the voltage striking distance in air from metal to metal of the voltage of operation, and said high voltage bushings having a radial length from the outer surface of said tank less than the voltage striking distance in air from metal to metal at said voltage of operation.

6. A housing for electrical apparatus having a frame and adapted for operation at high voltage, comprising an open topped tank, a domed cover complementary with the open top of said tank to close same, a compression clamp peripherally en aging said tank and said cover to join same together, first and second pairs of diametrically opposed closely spaced longitudinal ribs on the inner surface of said tank, first and second high voltage bushings located on opposite sides of a reference line near the top of said tank, first, second, and third closely spaced low voltage terminals located near the top of said tank on the side thereof opposite said reference line, electrical terminals extending through said tank at each of said high voltage bushings, said tank, clamp, cover, longitudinal ribs, and bushings being formed from dielectric material, a top and a bottom frame clamp adapted to engage said apparatus frame, said bottom frame clamp engaging a part of the inner surface of said tank to centrally locate the bottom of said frame, first and second leaf springs carried on opposite ends of said top frame clamp and resiliently engaging said first and second pairs of ribs to centrally locate the top of said frame and restrain sideways and upward movement thereof, said apparatus and the inner surface of said tank spaced less than the voltage striking distance in air from metal to metal on said high voltage, and said high voltage bushings having a radial length from the outer surface of said tank less than the voltage striking distance in air from metal to metal at said high voltage operation.

7. A housing for electrical apparatus having a frame, comprising an open topped tank, a domed cover complementary with the open top of said tank to close same, a compression clamp peripherally engaging said tank and said cover to join same together, a formed mounting bracket having a body portion and protruding ears, said body portion being disposed lengthwise on said tank and fitting the contour thereof, said ears having mounting holes, first and second lifting hooks near the top of said tank, first and second bands encircling said tank, lifting hooks and mounting bracket near the top and bottom, respectively, of said tank and said mounting bracket to join together said tank, lifting hooks and bracket, first and second pairs of diametrically opposed closely spaced integral longitudinal ribs on the inner surface of said tank, first and second pairs of diametrically opposed widely spaced lugs integral with the inner surface of the bottom of said tank, said pairs of lugs straddling said pairs of ribs, first and second high voltage bushings located on opposite sides of said mounting bracket near the top of said tank, low voltage terminals located near the top of said tank on the side thereof opposite said mounting bracket, electrical terminals extending through said tank at each of said high voltage bushings, said low voltage terminals and said high voltage bushings being substantially symmetrically spaced on the periphery of said tank, terminal knobs threadably engaging each of said terminals, said tank, cover, clamp, mounting bracket, lifting hooks, bands, longitudinal ribs, lugs, and bushings being formed from dielectric material, a top and a bottom frame clamp adapted to be fastened to said apparatus frame, said bottom frame clamp engaging each of said first and second pairs of lugs to centrally locate the bottom of said frame, first and second leaf springs carried on opposite ends of said top frame clamp and resiliently engaging said first and second pairs of ribs to centrally locate the top of said frame and restrain sideways and upward movement thereof, said apparatus adapted to be spaced from the inner surface of said tank a given distance, said high voltage bushings having a given radial length from the outer surface of said tank, said given distance and given radial length being less than the voltage striking distance in air from metal-to-metal at the voltage of operation.

8. A housing for electrical apparatus having a frame, comprising a generally cylindrical open topped tank having a substantially fiat bottom, a lip at the top of said tank, a circular domed cover having an integrally formed gasket recess and complementary with the lip at the open top of said tank to close same, a gasket in said gasket recess providing a seal With the top of said tank, a compression clamp peripherally engaging said tank and said cover to join same together, complementary notches in said lip and said cover under said clamp forming rain Water passageways, a formed mounting bracket having a body portion and four protruding ears, said body portion being partially cylindrical and disposed lengthwise on a first side of said tank and fitting the contour thereof, said four ears lying generally in a plane parallel to the axis of said cylindrical tank and which plane lies beyond the periphery of said tank, said ears having mounting holes, a first continuous band encircling said tank and mounting bracket near the top of said tank and mounting bracket, and a second continuous band encircling said tank and mounting bracket near the bottom of said tank and mounting bracket to join together said tank and bracket, first and second pairs of diametrically opposed closely spaced integral longitudinal ribs on the inner surface of saidtank, first and second pairs of diametrically opposed widely spaced lugs integral with the inner surface of the bottom of said tank, first and second high voltage bushings located on opposite sides of said mounting bracket near the top of said tank, electrical terminals extending through said tank at each of said high voltage bushings, first, second, and third closely spaced low voltage terminals located near the top of said tank on the side thereof opposite said mounting bracket and extending through said tank and making a fluid seal therewith, circular terminal knobs threadabiy engaging each of said terminals, said tank, cover, clamp, mounting bracket, continuous bands, longitudinal ribs, lugs, and bushings being formed from dielectric material, a top and a bottom frame clamp adapted to be fastened to said apparatus frame, said bottom frame clamp being generally rectangular and engaging each of said first and second pairs of lugs to centrally locate the bottom of said frame, first and second leaf springs clamped by first and second stiff members to opposite ends of said top frame clamp with said leaf springs resiliently engaging said first and second pairs of ribs to centrally locate the top of said frame and restrain upward movement thereof and with said stiff members restraining sideways movement of said frame, said apparatus adapted to be spaced from the inner surface of said tank a given distance, said high voltage bushings having a given radial length from the outer surface of said tank, said given length and given radial distance being less than the voltage striking distance in air from metal-to-rnetal at the voltage of operation.

9.. A housing for electrical apparatus having a frame and adapted for operation at high voltage, comprising an open topped tank, a domed cover complementary with the open top of said tank to close same, compression clamp peripherally engaging said tank and said cover to join same together, a formed mounting bracket having a body portion and four protruding ears, said body portion being dis 2d lengthwise on said tank and fitting the contour thereof, Sc. d four ears lying generally in a plane parallel to the :is of said cylindrical tank and lying beyond the p. sh 7y of said tank, said cars having mounting holes, first and second bands encircling said tank and mounting bracket near the top and bottom, respectively, of said tank and said mounting bracket, first and second pairs of diametrically opposed closely spaced longitudinal ribs on the inner surface of said tank,

i first and second high voltage bushings located on opposite sides of said mounting bracket near the top of said tank, first, second, and third closely spaced low voltage terminals located near the top of said ta on the side thereof opposite said mounting bracket, e cctrical terminals ex tending through said tank at each of said high voltage bushings, said. second low voltage terminal and said high voltage bushings being substantially symmetrically spaced on the periphery of said tank and in approximately the same plane normal to said tank axis, terminal knobs threadably engaging each of said terminals, said tank, clamp, cover, mounting bracket, bands, longitudinal ribs, and bushings being formed from dielectric material, a top and a bottom frame clamp adapted to engage the frame of said apparatus, said bottom frame clamp engaging a part of the inner surface of said tank to centrally locate the bottom of said frame, first and second leaf springs carried on opposite ends of said top frame clamp and. resiliently eng said first and second pairs of ribs to. centrally locate the top of said frame and restrain sideways and upward movement thereof, said apparatus adapted to extend to within a given distance of the inner surface of said tank, said high voltage bushings having a given radial length from the outer surface of said tank, and said given distance and given radial length being less than the. voltage striking distance in air from metal to metal at said high voltage operation.

10. A housing for electrical apparatus having a core and. a high. voltage winding and adapted for operation at distribution voltages, comprising a generally cylindrical open topped tank having a substantially flat bottom, a

circular domed cover having an integrally formed gasket recess and complementary with the open top of said tank to close same, a gasket in said gasket recess providing a seal with the top of said tank, a compression clamp peripherally engaging said tank and said cover to join same together, a formed mounting bracket having a body portion and four protruding ears, said body portion being partially cylindrical and disposed lengthwise on a first side of said tank and fitting the contour thereof, said four ears lying generally in a plane parallel to the axis of said cylindrical tank and lying beyond the periphery of said tank, said ears having mounting holes, first and second lifting hooks near the top of said tank, first and second continuous bands encircling said tank, lifting hooks and mounting bracket near the top and bottom, respectively, of said tank and said mounting bracket to join together said tank, lifting hooks and bracket, first and second pairs of diametrically opposed closely spaced integral longitudinal ribs on the inner surface of said tank, first and second pairs of diametrically opposed widely spaced lugs integral with the inner surface of the bottom of said tank, said pairs of lugs straddling said pairs of ribs, first and second high voltage bushings located on opposite sides of said mounting bracket near the top of said tank, first, second, and third closely spaced low voltage terminals located near the top of said tank on the side thereof opposite said mounting bracket, electrical terminals extending through said tank at each of said high voltage bushings and making a fluid seal with said tank, said second low voltage terminal and said high voltage bushings being substantially symmetrically spaced on the periphery of said tank and in approximately the same plane normal to said tank axis, circular terminal knobs threadably engaging each of said terminals, said tank, cover, clamp, mounting bracket, lifting hooks, continuous bands, longitudinal ribs, lugs, and bushings being formed from dielectric material, a top and a bottom core clamp adapted to engage and be fastened to the core of said apparatus, said bottom core clamp being generally rectangular and engaging each of said first and second pairs of lugs to centrally locate the bottom of said core, first and second leaf springs carried on opposite ends of said top core clamp and resiliently engaging said first and second pairs of ribs to centrally locate the top of said core and restrain sideways and upward movement thereof, said apparatus adapted to be spaced from the inner surface of said tank a given distance, said high voltage bushings having a given radial length from the outer surface of said tank, said given distance and given radial length being less than the voltage striking distance in air from metalto-metal at said high distribution voltage operation, and said tank adapted to be filled with dielectric oil 11. A housing for electrical apparatus having a core and a high voltage winding and adapted for operation at distribution voltages, comprising a generally cylindrical open topped tank having a substantially flat bottom, a lip at the top of said tank, a circular domed cover having an integrally formed gasket recess and complementary with the lip at the open top of said tank to close same, a gasket in said gasket recess providing a seal with the top of said tank, a compression clamp peripherally engaging said tank and said cover to join same together, complementary notches in said lip and said cover under said clamp forming rain water passageways, a formed mounting bracket having a body portion and four protruding ears, said body portion being partially cylindrical and disposed lengthwise on :a first side of said tank and fitting the contour thereof, said four ears lying generally in a plane parallel to the axis of said cylindrical tank and Which plane lies beyond the periphery of said tank, said ears having mounting holes, first and second lifting hooks near the top of said tank, a first continuous band encircling said tank, lifting hooks and mounting bracket near the top of said tank and mounting bracket, and a second continuous band encircling said tank and mounting bracket near the bottom of said tank and mounting bracket to join together said tank, lifting hooks, and bracket, first and second pairs of diametrically opposed closely spaced integral longitudinal ribs on the inner surface of said tank, first and second pairs of diametrically opposed widely spaced lugs integral with the inner surface of the bottom of said tank, each of said pairs of lugs straddling one of said pairs of ribs, first and second high voltage bushings located on opposite sides of said mounting bracket near the top of said tank, electrical terminals extending through said tank at each Of said high voltage bushings and making a fluid seal with said tank, first, second, and third closely spaced low voltage terminals located near the top of said tank on the side thereof opposite said mounting bracket and extend ing through said tank and making a fluid seal therewith, said second low voltage terminal and said high voltage bushings being substantially symmetrically spaced on the periphery of said tank and in approximately the same plane normal to said tank axis, circular terminal knobs threadably engaging each of said terminals, said tank, cover, clamp, mounting bracket, lifting hooks, continuous bands, longitudinal ribs, lugs, and bushings being formed from dielectric material, a top and .a bottom core clamp engaging and fastened to the core of said apparatus, said bottom core clamp being generally rectangular and engaging each of said first and second pairs of lugs to centrally locate the bottom of said core, first and second leaf springs clamped by first and second stiff members to opposite ends of said top core clamp with said leaf springs resiliently engaging said first and second pairs of ribs to centrally locate the top of said core and restrain upward movement thereof and with said stiff members restraining sideways movement of said core, said tank adapted to be filled with dielectric oil, said apparatus high voltage Winding adapted to be spaced from the inner surface of said tank a given distance, said high voltage bushings having a given radial length from the outer surface of said tank, said given length and given radial distance being less than the voltage striking distance in air from metalto-metal at said high distribution voltage operation.

12. A housing for electrical apparatus having a frame, comprising a tank and cover to close same, first and second pairs of longitudinal ribs on the inner surface of said tank, a frame clamp for engaging said frame, first and second leaf springs carried at opposite ends of said frame clamp, said leaf springs being harder than said ribs and being upwardly directed at an acute angle to partially dig into and resiliently engage said first and second pairs of ribs to centrally locate the top of said frame and restrain upward movement thereof.

13. A housing for electrical apparatus having a frame, comprising a tank and cover to close same, first and second pairs of diametrically opposed closely spaced longitudinal ribs on the inner surface of said tank, a top frame clamp for engaging said frame, and first and second leaf springs clamped by first and second stiff members at opposite ends of said top frame clamp, said leaf springs being harder than the material of said ribs and being upwardly directed at an acute angle to partially dig into and resiliently en age said first and second pairs of ribs to centrally locate the top of aid frame and restrain upward movement thereof, and said stiff members restraining sideways movement of said frame.

14. A housing for electrical apparatus having a frame, comprising a tank and cover to close same, locator means including first and second pairs of diametrically opposed closely spaced longitudinal ribs on the inner surface of said tank, .a top and a bottom frame clamp for engaging said apparatus frame, said bottom frame clamp being generally rectangular and engaging said locator means to centrally locate the bottom of said frame, first and second leaf springs clamped by first and second stiff members at opposite ends of said top frame clamp, said leaf springs being harder than the inner surface of said tank to resiliently engage said first and second pairs of ribs to cen- 'trally locate the top of said frame and restrain upward movement thereof, and said stiff members restraining sideway movement of said frame.

15. A housing for electrical apparatus having a frame, comprising a tank and cover to close same, first and second pairs of diametrically opposed closely spaced longitudinal ribs on the inner surface of said tank, first and second pairs of diametrically opposed widely spaced lugs on the inner surface of the bottom of said tank, said pairs of lugs straddling said pairs of ribs, a top and a bottom frame clamp for engaging said apparatus frame, said bottom frame clamp being generally rectangular and engaging each of said first and second pairs of lugs to centrally locate the bottom of said frame, first and second leaf springs clamped by first and second stiff members at opposite ends of said top frame clamp, said leaf springs being harder than said ribs to resiliently engage said first and second pairs of ribs to centrally locate the top of said frame and restrain upward movement thereof, and said stiff members restraining sideways movement of said frame.

16. A housing for electrical apparatus having a core and a high voltage winding and adapted for operation at distribution voltages, comprising a generally cylindrical open topped tank, a cover complementary with the open top of said tank to close same, a clamp engaging said tank and said cover to join same together, a formed mounting bracket having a body portion and four protruding ear-s, said body portion being partially cylindrical and disposed lengthwise on a first side of said tank and fitting the contour thereof, said four ears lying generally in a plane parallel to the axis of said cylindrical tank and which plane lies beyond the periphery of said tank, said ears having mounting apertures, first and second lifting hooks near the top of said tank, a first continuous band encircling said tank, lifting hooks and mounting bracket near the top of said tank and mounting bracket, and a second continuous band encircling said tank and mounting bracket near the bottom of said tank and mounting bracket to join together said tank, lifting hooks, and bracket, said tank, cover, clamp, mounting bracket, lifting hooks and continuous bands being formed from dielectric material.

17. A housing for electrical apparatus having a core and a high voltage winding and adapted for operation at distribution voltages, comprising a generally cylindrical open topped tank having a substantially flat bottom, a lip at the top of said tank, a circular domed cover having an integrally formed gasket recess and complementary with the lip at the open top of said tank to close same, a gasket in said gasket recess providing a seal with the top of said tank, a compression clamp peripherally engaging said tank and said cover to join same together, complementary notches in said lip and said cover under said clamp forming rain water passageways, a formed mounting bracket having a body portion and four protruding ears, said body portion being partially cylindrical and disposed lengthwise on a first side of said tank and fitting the contour thereof, said four ears lying generally in a plane parallel to the axis of said cylindrical tank and which plane lies beyond the periphery of said tank, said ears having mounting holes, first and second lifting hooks near the top of said tank, a first continuous band encircling said tank, lifting hooks and mounting bracket near the top of said tank and mounting bracket, and a second continuous band encircling said tank and mounting bracket to join together said tank, lifting hooks, and bracket, electrical terminals extending through said tank at each of said high voltage bushings and making a fluid seal with said tank, first, second, and third closely spaced low voltage terminals located near the top of said tank on the side thereof opposite said mounting bracket and extending through said tank and making a fluid seal therewith, said second low voltage terminal and said high voltage bushings being substantially symmetrically spaced on the periphery of said tank and in approximately the same plane normal to said tank axis, terminal knobs threadably engaging each of said terminals, said tank, cover, clamp, mounting bracket, lifting hooks, continuous bands, and bushings being formed from dielectric material, said tank adapted to be filled with dielectric oil, said apparatus high voltage winding adapted to be spaced from the inner surface of said tank a given distance, said high voltage bushings having a given radial length from the outer surface of said tank, said given length and given radial distance being less than the voltage striking distance in air from metal to metal at said distribution voltage operation.

References Cited in the file of this patent UNITED STATES PATENTS 1,832,671 Thompson et al. Nov. 17, 1931 1,867,394 Acly July 12, 1932 2,300,205 Christensen Oct. 27, 1942 2,739,917 Schulze Mar. 27, 1956 2,751,109 Moore June 19, 1956 

